Hardesty, Medulla Spinalis of the Elephant. 159 



kind. Considering excessive fat as abnormal, this could be 

 easily done in so limited a series. For example the variety of 

 cat used was appreciable larger as an adult than the adult white 

 rabbit. The ox (a large beef steer) has a larger body than the 

 average horse (an ordinary farm horse). The subject from 

 which the human material was obtained was estimated to weigh 

 160 pounds in health, an approximately average weight. 



The comparative studies here undertaken will deal with 

 transverse sections taken from one segment only of each of 

 the specimens. A comparison of the same segment throughout 

 the series ought to give most of the variations of interest which 

 would be shown by the much more tedious comparison of the 

 various segments throughout the series. 



The segment chosen for the purpose was that segment of 

 the intumescentia cervicalis which, in each case, possessed the 

 greatest mean diameter. In other words the sections compared 

 were taken transversely through the largest portions of the cer- 

 vical enlargements. Usually, this was the Vlth cervical seg- 

 ment. Beyond a comparison of the lateral and dorso-ventral 

 diameters of this largest cervical segment of each specimen, 

 no attempt is made to show differences in shape and gen- 

 eral topography of the sections and no illustrations are given of 

 the sections from the different animals. 



The studies will include only the following comparisons : 



I. Dimensions of the sections. 



Total areas of the sections. 

 Areas of the substantia alba in section. 

 Areas of the substantia grisea in section. 

 Ratio of area of section of substantia grisea to total 

 area of section. 



6. Ratios between the areas of the substantia grisea and 

 substantia alba. 



7. Average mean diameters of the largest cell-bodies of 

 the columnae anteriores. 



8. Volumes of the neurones whose cell-bodies are situ- 

 ated in the columnae anteriores. 



